Searching for a SARS-CoV-2 Vaccine
Could a vaccine for the SARS-CoV-2 virus be in our near future?
Could a vaccine for the SARS-CoV-2 virus be in our near future? Recent articles in The Wall Street Journal, The New York Times and Scientific American detail plans for developing a vaccine to help stem the COVID-19 pandemic. These reports examine the widespread efforts to develop these medications, and discuss roadblocks to producing and delivering a workable vaccine on a global scale.
One of the hurdles facing a vaccine for use in the United States is the rigorous process of achieving approval from the U.S. Food and Drug Administration. In the past, this took years, and even then less than 10% of the products entering this pipeline were ultimately approved for distribution. In this case, the investment is worthwhile, since the potential rewards — both in human lives and economic gain — are staggering.
As of this writing, plans call for Phase 3 trials to start in late summer or early fall. Efficacy will be evaluated over a period of months. Assuming a successful outcome, the vaccine would be distributed first to areas with high mortality.
In the past, vaccines for flu viruses were made using educated guesses of the virus’ genetic structure. To our advantage, many of the current forms of the coronavirus have been identified, and vaccines can be formulated using this data.
ASSUMING A SUCCESSFUL VACCINE IS DEVELOPED, THERE ARE STILL MORE QUESTIONS THAN ANSWERS ABOUT HOW IT WILL BE MASS-PRODUCED AND DELIVERED.
Currently, there are two methods for developing a vaccine: one is the traditional approach used for the flu vaccine; the other is based on the use of manufactured DNA or RNA. The traditional approach uses viruses that are grown, then attenuated, killed or separated into pieces and, ultimately, injected parenterally. While successful in the past, this method is time-consuming and expensive. In addition, there is concern over how long it will take to produce the needed number of doses.
At present, the use of manufactured DNA or RNA is the most promising approach. The goal in developing these genetically engineered vaccines is to make an antigen that replicates the spike protein used by the virus to attach to the host cell. One company uses snippets of the viral RNA in a lipid carrier that is injected and then ingested by the cell, leading to immunity. While RNA vaccines are relatively easy to make, they are less stable than their DNA counterparts and must be kept frozen, thus creating challenges for widespread distribution.
Several companies are using viruses to deliver DNA snippets. One group is using a weakened, nonreplicating common cold virus that contains a DNA replica of the spike protein. Another is producing a gene-based vaccine that is loaded onto a modified chimpanzee cold virus, which the patient inhales.
No vaccine is currently approved. To hold Phase 3 trials this early in the development process is a significant acceleration compared to previous vaccine preparation. However, it is estimated it will take several months after the start of Phase 3 trials for definitive answers. Assuming a successful vaccine is developed, there are still more questions than answers about how it will be mass-produced and delivered.
We all hope for an early and effective answer.
Thomas G. Wilson Jr., DDS
Editor in Chief
From Decisions in Dentistry. July/August 2020;6(7):6.